Works of the founder of Anarchism Mikhail Bakunin (1814-1876) or published collections of works of Bakunin.
(for biographies of Bakunin see here)
Books
Statism and Anarchy (1990), Cambridge University Press, ISBN 0521361826
Containing his most fully-developed critique of Marx and his methods, Statism and Anarchy was Bakunin's only book-length publication in his lifetime.
https://libcom.org/library/statism-anarchy-mikhail-bakunin
God and the State (1882)
https://libcom.org/library/god-and-state-mikhail-bakunin
Audiobook
https://libcom.org/library/god-state-mikhail-bakunin-audiobook
Other writings
Stateless Socialism: Anarchism (1953)
https://libcom.org/library/stateless-socialism-anarchism-mikhail-bakunin
Marxism, Freedom, and the State (1950)
https://libcom.org/library/marxism-freedom-state-mikhail-bakunin
The Paris Commune and the Idea of the State (1871)
https://www.marxists.org/reference/archive/bakunin/works/1871/paris-commune.htm
The Immorality of the State (1953)
https://www.marxists.org/reference/archive/bakunin/works/various/state-im.htm
Revolutionary Catechism (1866)
https://www.marxists.org/reference/archive/bakunin/works/1866/national-catechism.htm
The Commune, the Church, and the State (1947)
https://libcom.org/library/commune-church-state-mikhail-bakunin
Founding of the First International (1953)
On Rousseau (1972)
http://dwardmac.pitzer.edu/Anarchist_Archives/bakunin/rousseau.html
Anthologies
Bakunin's writings (1947) Guy Aldred
https://libcom.org/library/bakunins-writings-guy-aldred
Bakunin on Anarchy (1972) Sam Dolgoff
https://libcom.org/library/bakunin-anarchy-selected-works-activist-founder-world-anarchism
Mikhail Bakunin:, Selected Writings (Writings on the Left) (1973) Arthur Lehning
https://libcom.org/library/michael-bakunin-selected-writings
Qualitatively the best.
Further resources
See also
Libertarian Labyrinth Bakunin archive
https://www.libertarian-labyrinth.org/bakunin-library/welcome-bakunin-library/
http://dwardmac.pitzer.edu/Anarchist_Archives/bakunin/Bakuninbiblio.html
Comments
A few more: Federalism,
A few more:
Federalism, Socialism, Anti-Theologism (1867)
Letters on Patriotism (1869)
Bakunin:On the Policy of the IWMA (1869)
Science and the Urgent Revolutionary Task (1870)
Letter to La Liberte (1872)